1. Field of the Invention
This invention relates to a dialer circuit for controlling the dialing in a telephone, and more particularly to a reset circuit for restoring the normal operation of a dialer when the dialer is about to make a reckless driving.
2. Description of the Related Art
As great advances have been made in recent years in semiconductor technology, the application of control systems using ICs, ISIs, etc. to various machines and equipments are on the rise. Telephones are not an exception; their operation is performed under the control of ICs, for example, in which a variety of functions are incorporated. Many of modern telephones have the function of memorizing a preset telephone number several times and automatically dialing the preset telephone number in a simple operation. Generally, such automatic dialing function is performed by an dialer composed of a microcomputer built in the telephone.
In this type of telephone, when the dialer makes a reckless driving or stampede due to external noises, for example, a predetermined dialing operation is difficult to achieve. For restoring it to the normal operation, it is necessary to bring the telephone back to its initial state by resetting.
Consequently, the conventional telephone also is equipped with a reset button for resetting the system of a dialer and the entire telephone as well. Further, in a telephone having no reset button, the resetting operation must be performed by switching off the power source to terminate all the operations of a dialer and then switching on the power source so that a reset signal is issued in the telephone to restore the initial state of the telephone.
In this conventional dialer, its reckless driving is prevented by making a resetting with a reset button or by switching off the power source to stop the operation of the dialer. However, according to such conventional resetting method, the microcomputerdialer would necessarily be brought back to its initial state. Generally in the dialer, since there is incorporated a program so as to erase the contents of a memory at the time of initial setting, a telephone number or other data memorized in a telephone would be deleted. When the telephone number in the memory have once been erased, then the user must take the trouble of inputting the telephone number again, which is laborious and time-consuming.